Corrosion nonelectrochemical study

Nonelectrochemical Methods. Nonelectrochemical methods of studying corrosion include exposure tests of performance and primary film property measurements. Standard exposure tests include salt water immersion (3-5% aq. NaCl, usually at room temperature, sometimes oxygen saturated) cyclic immersion (e.g., salt water immersion alternated with drying periods) salt fog or spray (5% aq. NaCl fog,... 

Many different electrochemical and non-electrochemical techniques exist for the study of corrosion and many factors should be considered when selecting a technique. Corrosion rate can be determined by Tafel extrapolation from a potentiodynamic polarization curve. Corrosion rate can also be determined using the Stem-Geary equation from the polarization resistance derived from a linear polarization or an electrochemical impedance spectroscopy (EIS) experiment. Techniques have recently been developed to use electrochemical noise for the determination ofcorrosion rate. Suscephbility to localized corrosion is often assessed by the determination of a breakdown potenhal. Other techniques exist for the determinahon of localized corrosion propagahon rates. The various electrochemical techniques will be addressed in the next section, followed by a discussion of some nonelectrochemical techniques. 

The most common nonelectrochemical approach for the study of corrosion is weight loss measurements. Such measurements are limited by the resolution of the gravimetric device, and, for aqueous corrosion, are usually applied in aggressive environments such as the boiling acids used to evaluate sensitization of stainless steels in ASTM A262 [76]. The Quartz Crystal Microbalance (QCM) is a gravimetric instrument capable of submonolayer sensitivity that has been increasingly applied over recent years in the area of corrosion [85, 86]. 

For over a decade, the use of poly aniline for corrosion protection of metals, particularly stainless steel, has been investigated. In the first study [105] by DeBerry, polyaniline was electrochemically deposited on ferritic stainless steels and found to provide anodic protection that significantly reduced corrosion rates in acid solutions. Numerous studies since then have confirmed the corrosion-preventing properties of polyanilines [102-104,106-111]. In addition, nonelectrochemical methods of applying polyaniline have been demonstrated [102-104,106-1111. In one recent study (I09J, dispersions based on doped polyaniline. Versicon, ... 

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